Sewing machine with stepper feed



Nov. 21, 1961 R. REEBER EI'AL SEWING MACHINE WITH STEPPER FEED 2Sheets-Sheet 1 Filed July 18, 1960 FIG. I

"2 5% J m 6 M Z WWW 2 Nov. 21, 1961 R. REEBER ETAL SEWING momma WITHSTEPPER FEED 2 Sheets-Sheet 2 Filed July 18, 1960 IN VEN T0195Pudo/HPEEBEP f/e/muf- 6,0055

United States Patent Ofihce 3,009,432 Patented Nov. 21, 1961 SEWINGMACHINE WITH STEPPER FEED Rudolf Reeber and Helmut Gross,Kaiserslautern, Pfalz,

Germany, assigno-rs to G. M. Pfaff A.-G., Kaiserslautern, Pfalz, GermanyFiled July 1%, 1960, Ser. No. 43,366 Claims priority, applicationGermany July 30, 1959 (Claims. (Cl. 112--212) The present inventionrelates to a sewing machine having a top feeding arrangement whichoperates by means of axially movable lifting "bars for the top feedstepper foot and for the presser foot.

In sewing machines having top feeding means of the type knownheretofore, the lifting bars for the feeding foot and for the presserfoot are arranged one behind the other with respect to the direction offeed. The lifting bar for the top feeding foot in this connection isjournalled in a rocking member which makes it possible to impart feedingmovements to the top feeding foot which is connected thereto.

A rocking device of this type involves bulky components and thereforeincreases the mass which has to be moved. In top feeding arrangements ofthis type, both lifting bars execute thrust movements in rapidlychanging alternate sequence which further increase the momentum.Particularly by raising the speed of operation the mass forces canincrease to such an extent that the feet which alternately engage thematerial being sewn no longer touch the material at the correct time andwith the required pressure. This results in irregularities in the feedwhich may affect the equality of stitch length.

In accordance with the invention a top feed mechanism is provided whichcan be accommodated in a small space and by means of which the movingmasses are reduced so that highest operating speeds are possible. Thisproblem is solved in that the lift bars for the top feed foot and forthe presser foot are arranged one within the other and a sliding fork ofthe top feed foot slidingly engages a sliding block fastened to thelower end of the lift bar for the top feed foot. In this manner thestructural form of the top feed mechanism is considerably simplified inspite of crowded structural conditions.

In accordance with an object of the invention, the mass forces arereduced to a particularly great extent, if in a top feed arrangementhaving a spring alternately biasing the two lift bars and a angularlever which performs a rocking movement and which is pivotally mountedon one of the lift bars, the spring acts upon the lift bar for the topfeed foot and tone end of the angular lever temporarily engages thislift bar for operation.

In this manner the presser foot is not raised during the feeding of thematerial but is only relieved of the pressure of the spring. Thematerial being sewn which is under it can be advanced without beingimpeded by the top feed foot. The movements of the presser foot, as Wellas those of the lift bar, are as a result of this measure reduced to theminimum amounts which are the result of the difference between normaland compressed material thickness so that the mass forces becomenegligible.

An intermediate member which is rigidly connected with the lift bar forthe top feed foot serves as a support for the spring and as abutment forthe end of the angular lever.

The top feed arrangement in accordance with the invention provides theadditional advantage of establishing the requisites for using a cuttingarrangement in that the transfer of the lifting movement for the topfeed foot and the cutter takes place by way of common elements for asufficient length of time until the disengageable operating means for,the cutter is removed. This simple arrangement results from a clampingmember which 18 rigidly connected with the shaft and which has two arms,one of which is connected by way of a link to the angular lever and theother carries a slide bar on which a slide member which actuates thecutter thrust bar is slidably mounted for movement by means :of ashifting lever. The top feed arrangement in accordance with theinvention can in this manner be operated without reducing the speed andin spite of the additionally provided cutting arrangement.

Further objects and details of the invention, as well as the advantagesprovided thereby will become apparent from the following specificationwith reference to the embodiment illustrated in the accompanyingdrawings In which:

FIG. 1 is a front view of a sewing machine provided with the mechanismin accordance with the invention;

FIG. 2 is a perspective view of the top feed mechanism assembly and ofthe cutting arrangement of the machine;

FIG. 3 is an enlarged view of the top feed and of the material presserfoot shown in FIG. 1; and

FIG. 4 is a perspective view of the arrangement of the angular lever.

The arm shaft 1 which is driven in the conventional manner carries a cam2 (FIG. 2) which moves a cam bar 3. The other end of the cam bar 3 isprovided on both sides with slide blocks 4, 5. The slide block 4 isguided in a slotted member 6. The direction of the path of theadjustable slotted member 6 is determined by a setting shaft 7 which isjournalled in the housing of the sewing machine having a lever 8(FIG. 1) extending from the housing.

Owing to the directional guiding of the slide block 4 (FIG. 2) in theslotted member 6, the slide block 5 turns a lever 9 which is looselyjournalled by means of an apertured member 10 on a rocking shaft 11disposed in the housing of the machine. The rotational movement of thelever 9 is transferred to a bar 13 by way of a stud 12 secured to theend thereof and from this bar by way of a joint 14 to a double armedlever 15. This double armed lever 15 is pivotally mounted on a shaft 16which is secured to the housing of the sewing machine. The second arm ofthe double armed lever 15 is rotatably journalled in a fork 17 of a topfeed foot 18. The length of the forward and rearward feeding path isvariable. It depends upon the position of the adjustable slotted member6.

Tue lifting movement of the upper feed foot 18 is likewise controlled bythe arm shaft 1 from which the movement is transmitted to the rockingshaft 11 by way of a cam 19, a cam bar 20 and a crank 21. The rockingshaft 11 is provided at its forward end with a clamp member 22 which hastwo arms 23 and 24. Arm 23 transmits the rotational movement of therocking shaft 11 to an angular lever 26 by way of a link 25. Asparticularly shown in FIG. 4, the angular lever 26 is rotatablyjournalled on a stud 27. The stud 27 is a part of a clamp member 28which is secured upon a tubular lift bar 29. A presser foot 30 (FIG. 3)is connected to this lift bar 29 at the lower end thereof and pressesdown upon a stitch plate 31. The angular lever 26 (FIG. 4) supports aroller 32 at its upper end (FIG. 4). If the angular lever 26 is moved inthe direction of the upper dead center of its path by means of member25. the roller 32 engages below an intermediate member 33 which issecured to a lift bar 34 and thus raises the lift bar 34 which is underthe pressure of a spring 35. The

spring 35 is secured to the housing. The lift bar 34 slides in thetubular lift bar 29 and carries a slide member 36 (FIG. 2) at its lowerend which is engaged by -a 3 sliding fork 37 of the upper feed foot 18and turns the same about its pivot in forked member 17 raising it fromthe stitch plate 31.

If the roller 32 of the angular lever 26 is in its lowermost position,it disengages the intermediate member 33. In this manner the angularlever 26 and thus also the lift bar 29 with the presser foot 30 isrelieved of the pressure of the spring 35. The material can slide underthe pressure foot 39 because this foot rests on the stitch plate 31 onlyunder the weight of the angular lever 26, lift bar 29 and its ownweight. Thus, the presser foot 30 is not raised during the time that thepressure of spring 35 is completely transmitted to the top feed foot 18.

A cutter 38 arranged proximate the presser foot 30 is likewise driven bythe clamp member 22 of the rocking shaft 11. The arm 24- of the clampmember 22 supports a slide bar 39 which effects rocking movements aboutthe rocking shaft 11. These rocking movements are transferred by a slidemember 40 through a guide member 41 to a cutter thrust bar 42 which isjournalled in the housing of the machine. The cutter thrust bar 42 has ablade support 43 at its lower end to which the cutter 33 is secured.

If the cutter is to be disconnected and brought into idling position,the shifting lever 44 is moved upwardly. A shifting bar 45 which has anangularly bent arm 46 by means of which it is rotatably mounted in thehousing of the machine and which is connected with the shifting lever 44presses the slide member 40 on the slide bar 39 in the direction of arm24 of the clamp member 22 by way of a slide sleeve 47 which has a stud48. If at the end of the disconnecting operation the engagement positionbetween-the guide member 41 and the slide member 40 is disposed exactlyin the axis of rotation of rocking shaft 11, then the movement of theguide member 41 is substantially zero because the length of theeffective lever arm of the slide bar 49 for driving the cutter 38becomes substantially zero. In synchronism with the disconnectingmovement the sliding member 40 draws the cutter thrust bar 42 upwardlyby way of link 41 and thus raises the cutter 33 over the stitch plate 31so far that a space is formed between cutter 38 and stitch plate 31 andthus the cutter is rendered inoperative.

Having now described our invention with reference to the embodimentillustrated, we do not wish to be limited thereto, but what we desiredto protect by Letters Patent is set forth in the appended claims.

We claim:

1. Sewing machine with top feeding mechanism comprising, in combinationwith a machine housing, a drive shaft, a pair of axially movable liftbars operatively linked to said drive shaft and including a top feed barand a presser foot bar mounted for axial movement in said housing, a topfeed lever pivotally mounted in said housing, a top feed foot pivotallysupported on said lever and a presser foot mounted on the lower end ofsaid presser foot bar, said bars being arranged telescopically onewithin the other, a slide fork disposed on said top feed foot, a slidingblock disposed on the lower end of said top feed bar and extendinglaterally therefrom into sliding engagement with said slide fork andmeans connecting said lever for rocking movement to said drive shaft.

2. Sewing machine with top feeding mechanism comprising, in combinationwith a machine housing, a drive shaft, a pair of axially movable liftbars operatively linked to said drive shaft and including a top feed barand a presser foot bar mounted for axial movement in said housing, a topfeed lever pivotally mounted in said housing, a top feed foot pivotallysupported on said lever and a presser foot mounted on the lower end ofsaid presser foot bar, said bars being arranged telescopically onewithin the other, a slide fork disposed on said top feed foot, a slidingblock disposed on the lower end of said top feed bar and extendinglaterally therefrom into sliding engagement with said slide fork, meansconnecting said lever for rocking movement to said drive shaft, anangular lever rockably mounted at the upper end of said presser foot barand a spring supported in said housing in biasing relation to the upperend of said top feed bar, one arm of said angular lever being adapted totemporarily engage a member of said top feed bar.

3. Sewing machine with top feeding mechanism comprising, in combinationwith a machine housing, a drive shaft, a pair of axially movable liftbars operatively linked to said drive shaft and including a top feed barand a presser foot bar mounted for axial movement in said housing, a topfeed lever pivotally mounted in said housing, a top feed foot pivotallysupported on said lever and a presser foot mounted on the lower end ofsaid presser foot bar, said bars being arranged telescopically onewithin the other, a slide fork disposed on said top feed foot, a slidingblock disposed on the lower end of said top feed bar and extendinglaterally therefrom into sliding engagement with said slide fork, meansconnecting said lever for rocking movement to said drive shaft, anangular lever roackably mounted at the upper end of said presser footbar and a spring supported in said housing in biasing relation to theupper end of said top feed bar, one arm of said angular lever beingadapted to temporarily engage a member of said top feed bar, said memberof said top feed bar being an intermediate member rigidly secured tosaid top feed bar having engagement with said spring and defining anabutment for one arm of said angular lever.

4. Sewing machine with top feeding mechanism comprising, in combinationwith a machine housing, a drive shaft, a pair of axially movable liftbars operatively linked to said drive shaft and including a top feed barand a presser foot bar mounted for axial movement in said housing, a topfeed lever pivotally mounted in said housing, a top feed foot pivotallysupported on said lever and a presser foot mounted on the lower end ofsaid presser foot bar, said bars being arranged telescopically onewithin the other, a slide fork disposed on said top feed foot, a slidingblock disposed on the lower end of said top feed bar and extendinglaterally therefrom into sliding engagement with said slide fork, meansconnecting said lever for rocking movement to said drive shaft, anangular lever rockably mounted at the upper end of said presser foot barand a spring supported in said housing in biasing relation to the upperend of said top feed bar, one arm of said angular lever being adapted totemporarily engage a member of said top feed bar, said member of saidtop feed bar being an intermediate member rigidly secured to said topfeed bar having engagement with said spring and defining an abutment forone arm of said angular lever, said mechanism including a cutting deviceand a rocking shaft operatively connected to said cutting device andsaid cutting device having a disengageable cutter bar, and a clampmember having a pair of arms mounted on said rocking shaft, one of saidarms being in engagement with said angular lever by way of a link andthe other carrying a sliding rod slidingly supporting a cutter thrustbar and slide member, and a shifting lever mounted in said housinghaving engagement with said slide member.

5. Sewing machine with top feeding mechanism comprising, in combinationwith a machine housing, a drive shaft, a pair of axially movable liftbars operatively linked to said drive shaft and including a top feed barand a presser foot bar mounted for axial movement in said housing, a topfeed lever pivotally mounted in said housing, a top feed foot pivotallysupported on said lever and a presser foot mounted on the lower end ofsaid presser foot bar, said bars being arranged telescopically onewithin the other, a slide fork disposed on said top feed foot, a slidingblock disposed on the lower end of said top feed bar and extendinglaterally therefrom into sliding engagement with said slide fork, meansconnecting said lever for rocking movement to said drive shaft, anangular lever rockably mounted at the upper end of said presser foot barand a spring supported in said housing in biasing re lation to the upperend of said top feed bar, one arm of said angular lever being adapted totemporarily engage a member of said top feed bar, said member of saidtop feed bar being an intermediate member rigidly secured to said topfeed bar having engagement with said spring and defining an abutment forone arm of said angular lever, said mechanism including a cutting deviceand a rocking shaft operatively connected to said cutting device andsaid cutting device having a disengageable cutter bar, and a clampmember having a pair of arms mounted on said rocking shaft, one of saidarms being in engagement with said angular lever by way of a link andthe other carrying a sliding rod slidingly supporting a cutter 151,550,418

thrust bar and slide member, and a shifting lever mounted in saidhousing having engagement with said slide member, and a link extendingbetween said cutter thrust bar and said slide member at a joint movablewith said slide member by means of said shifting lever from a pointsubstantially in axial alignment with the cutter thrust bar to apoint'in axial alignment with said rocking shaft, said link beingsimultaneously operative to withdraw the cutter bar to idling position.

References Cited in the file of this patent UNITED STATES PATENTS253,731 Luessen Feb. 14-, 1882 Bates Aug. 18, 1925

